1. Re-lock your bootloader (this will most probably wipe content of your device)
2. Copy downloaded .zip to fastboot.exe location (e.g. c:/SDK/platform-tools/fastboot.exe)
3. Re-name .zip file to firmware.zip
4. Open command prompt
5. Boot your device in fastboot mode (vol down + power ===> fastboot)
6. Connect device to the PC
7. In command prompt cd to fastboot.exe location
8. Make sure you have correct modeid and cidnum (type: fastboot getvar all)
9. Type: fastboot oem lock (if your device is not relocked yet)
10. Type: fastboot oem rebootRUU and wait for device to reboot
11. Type: fastboot flash zip firmware.zip and wait for process to complete
12. Sometimes flashing for the first time doesn't work, so flash firmware.zip again just to make sure.
13. Type: fastboot flash zip firmware.zip and wait for process to complete
14. Type: fastboot reboot
15. Unlock your bootloader and flash custom recovery if you are going to use custom ROM.
But now the phone doesnt appear to boot im able to get into bootloader by holding down the volume button, any ideas why i cant boot into the HTC ONE do i need to re unlock the boot loader? If so how do you re unlock the boot loader after relocking it please?
EDIT: Im guess the phone doesnt boot as i need to flash a custom ROM??....if so do i have to re unlock the bootloader first?